scholarly journals Cilia Distal Domain: Diversity in Evolutionarily Conserved Structures

Cells ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 160 ◽  
Author(s):  
Helena Soares ◽  
Bruno Carmona ◽  
Sofia Nolasco ◽  
Luís Viseu Melo ◽  
João Gonçalves
Keyword(s):  
Cell Surface ◽  
Current Knowledge ◽  
Intraflagellar Transport ◽  
Basic Structure ◽  
Structure And Function ◽  
Single Organism ◽  
Evolutionarily Conserved ◽  
And Function ◽  
High Degree ◽  
Structure Diversity

Eukaryotic cilia are microtubule-based organelles that protrude from the cell surface to fulfill sensory and motility functions. Their basic structure consists of an axoneme templated by a centriole/basal body. Striking differences in ciliary ultra-structures can be found at the ciliary base, the axoneme and the tip, not only throughout the eukaryotic tree of life, but within a single organism. Defects in cilia biogenesis and function are at the origin of human ciliopathies. This structural/functional diversity and its relationship with the etiology of these diseases is poorly understood. Some of the important events in cilia function occur at their distal domain, including cilia assembly/disassembly, IFT (intraflagellar transport) complexes’ remodeling, and signal detection/transduction. How axonemal microtubules end at this domain varies with distinct cilia types, originating different tip architectures. Additionally, they show a high degree of dynamic behavior and are able to respond to different stimuli. The existence of microtubule-capping structures (caps) in certain types of cilia contributes to this diversity. It has been proposed that caps play a role in axoneme length control and stabilization, but their roles are still poorly understood. Here, we review the current knowledge on cilia structure diversity with a focus on the cilia distal domain and caps and discuss how they affect cilia structure and function.

scholarly journals Structure and Function of the CFTR Chloride Channel

1999 ◽  
Vol 79 (1) ◽  
pp. S23-S45 ◽  
Author(s):  
DAVID N. SHEPPARD ◽  
MICHAEL J. WELSH
Keyword(s):  
Cystic Fibrosis ◽  
Chloride Channel ◽  
Atp Hydrolysis ◽  
Current Knowledge ◽  
Structure And Function ◽  
Binding Domains ◽  
Transporter Family ◽  
Membrane Spanning ◽  
And Function ◽  
R Domain

Sheppard, David N., and Michael J. Welsh. Structure and Function of the CFTR Chloride Channel. Physiol. Rev. 79 , Suppl.: S23–S45, 1999. — The cystic fibrosis transmembrane conductance regulator (CFTR) is a unique member of the ABC transporter family that forms a novel Cl− channel. It is located predominantly in the apical membrane of epithelia where it mediates transepithelial salt and liquid movement. Dysfunction of CFTR causes the genetic disease cystic fibrosis. The CFTR is composed of five domains: two membrane-spanning domains (MSDs), two nucleotide-binding domains (NBDs), and a regulatory (R) domain. Here we review the structure and function of this unique channel, with a focus on how the various domains contribute to channel function. The MSDs form the channel pore, phosphorylation of the R domain determines channel activity, and ATP hydrolysis by the NBDs controls channel gating. Current knowledge of CFTR structure and function may help us understand better its mechanism of action, its role in electrolyte transport, its dysfunction in cystic fibrosis, and its relationship to other ABC transporters.

scholarly journals Minimal art: Or why small viral K+ channels are good tools for understanding basic structure and function relations

2011 ◽  
Vol 1808 (2) ◽  
pp. 580-588 ◽  
Author(s):  
Gerhard Thiel ◽  
Dirk Baumeister ◽  
Indra Schroeder ◽  
Stefan M. Kast ◽  
James L. Van Etten ◽  
...  
Keyword(s):  
Basic Structure ◽  
Structure And Function ◽  
K Channels ◽  
Minimal Art ◽  
And Function

scholarly journals The enigmatic ribosomal stalk

2018 ◽  
Vol 51 ◽  
Author(s):  
Anders Liljas ◽  
Suparna Sanyal
Keyword(s):  
Early Phase ◽  
Ribosomal Subunit ◽  
Structure And Function ◽  
Large Ribosomal Subunit ◽  
Translation Factors ◽  
Ribosomal Stalk ◽  
And Function ◽  
High Degree

Abstract The large ribosomal subunit has a distinct feature, the stalk, extending outside the ribosome. In bacteria it is called the L12 stalk. The base of the stalk is protein uL10 to which two or three dimers of proteins bL12 bind. In archea and eukarya P1 and P2 proteins constitute the stalk. All these extending proteins, that have a high degree of flexibility due to a hinge between their N- and C-terminal parts, are essential for proper functionalization of some of the translation factors. The role of the stalk proteins has remained enigmatic for decades but is gradually approaching an understanding. In this review we summarise the knowhow about the structure and function of the ribosomal stalk till date starting from the early phase of ribosome research.

Regulation of sperm motility at the axonemal level

1995 ◽  
Vol 7 (4) ◽  
pp. 847 ◽  
Author(s):  
C Gagnon
Keyword(s):  
Direct Action ◽  
Mammalian Species ◽  
Basic Structure ◽  
Structure And Function ◽  
Structural Components ◽  
Long Period ◽  
Different Types ◽  
Radial Spokes ◽  
Dynein Arms ◽  
And Function

With very few exceptions, the basic structure of the 9+2 axoneme has been well preserved over a very long period of evolution from protozoa to mammais. This stability indicates that the basic structural components of the axoneme visible by electron microscopy, as well as most of the other unidentified components, have withstood the passage of time. It also means that components of the 9+2 axoneme have sufficient diversity in function to accommodate the various types of motility patterns encountered in different species of flagella. Several of the 200 polypeptides that constitute the axoneme have been identified as components of the dynein arms, radial spokes etc. but many more remain to be identified and their function(s) remain to be determined. Because this review deals with the regulation of flagellar movement at the axonemal level, it does not include regulation of flagella by extracellular factors unless these factors have a direct action on axonemal components. In this context, it is very important firstly to understand the structural components of the axoneme and how they influence and regulate axonemal movement. Different primitive organisms are mentioned in this review since major breakthroughs in our understanding of how an axoneme generates different types of movement have been made through their study. Despite some variations in structure and function of axonemal components, the basic mechanisms involved in the regulation of flagella from Chlamydomonas or sea urchin spermatozoa should also apply to the more evolved mammalian species, including human spermatozoa.

scholarly journals The Significance of Calcium in Photosynthesis

2019 ◽  
Vol 20 (6) ◽  
pp. 1353 ◽  
Author(s):  
Quan Wang ◽  
Sha Yang ◽  
Shubo Wan ◽  
Xinguo Li
Keyword(s):  
Signal Transduction ◽  
Binding Sites ◽  
Current Knowledge ◽  
Structure And Function ◽  
Biochemical Reactions ◽  
Chloroplast Proteins ◽  
Secondary Messenger ◽  
And Function ◽  
The Relationship ◽  
Physiological And Biochemical

As a secondary messenger, calcium participates in various physiological and biochemical reactions in plants. Photosynthesis is the most extensive biosynthesis process on Earth. To date, researchers have found that some chloroplast proteins have Ca2+-binding sites, and the structure and function of some of these proteins have been discussed in detail. Although the roles of Ca2+ signal transduction related to photosynthesis have been discussed, the relationship between calcium and photosynthesis is seldom systematically summarized. In this review, we provide an overview of current knowledge of calcium’s role in photosynthesis.

scholarly journals Mathematical Modelling of the Structure and Function of the Lymphatic System

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1467
Author(s):  
Anastasia Mozokhina ◽  
Rostislav Savinkov
Keyword(s):  
Lymph Nodes ◽  
Mathematical Modelling ◽  
Mathematical Models ◽  
Lymphatic System ◽  
Current Knowledge ◽  
Structure And Function ◽  
Lymph Flow ◽  
And Function

This paper presents current knowledge about the structure and function of the lymphatic system. Mathematical models of lymph flow in the single lymphangion, the series of lymphangions, the lymph nodes, and the whole lymphatic system are considered. The main results and further perspectives are discussed.

Structure and function of complement C5 convertase enzymes

2002 ◽  
Vol 30 (6) ◽  
pp. 1006-1010 ◽  
Author(s):  
M. K. Pangburn ◽  
N. Rawal
Keyword(s):  
Cell Surface ◽  
Alternative Pathway ◽  
Membrane Attack Complex ◽  
Structure And Function ◽  
Regulatory Proteins ◽  
Covalent Attachment ◽  
Cleavage Rate ◽  
And Function ◽  
Natural Decay ◽  
The Complement System

The multisubunit enzymes of the complement system that cleave C5 have many unusual properties, the most striking of which is that they acquire their specificity for C5 following cleavage of another substrate C3. C5 convertases are assemblies of two proteins C4b and C2a (classical or lectin pathways) or C3b and Bb (alternative pathway) and additional C3b molecules. The catalytic complexes (C4b, C2a or C3b, Bb) are intrinsically unstable (t1,2 = 1–3 min) and the enzymes are controlled by numerous regulatory proteins that accelerate this natural decay rate. Immediately after assembly, the bi-molecular enzymes preferentially cleave the protein C3 and exhibit poor activity toward C5 (a Km of approx. 25 μM and a C5 cleavage rate of 0.3-1 C5/min at Vmax). Efficient C3 activation results in the covalent attachment of C3b to the cell surface and to the enzyme itself, resulting in formation of C3b-C3b and C4b-C3b complexes. Our studies have shown that deposition of C3b alters the specificity of the enzymes of both pathways by changing the Km for C5 more than 1000-fold from far above the physiological C5 concentration to far below it. Thus, after processing sufficient C3 at the surface of a microorganism, the enzymes switch to processing C5, which initiates the formation of the cytolytic membrane attack complex of complement.

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